Add to word and save

            Object oMissing = System.Reflection.Missing.Value;

            Object oFalse = false;

            Word.Application oWord = new Word.Application();
            Word.Document oWordDoc = new Word.Document();
            oWord.Visible = true;
            oWordDoc = oWord.Documents.Add(ref oMissing, ref oMissing, ref oMissing, ref oMissing);       
            Object start = 0;
            Object end = 0;
            Word.Range rng1 = oWordDoc.Range(ref start, ref end);

            rng1.Select();

            s4 = "The text to insert at the end of word"

            rng1.InsertAfter(s4);

            Object oSaveAsFile = (Object)"File location   ----  C:\\SampleDoc.docx";
            oWordDoc.SaveAs(ref oSaveAsFile, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing);

             oWordDoc.Close(ref oFalse, ref oMissing, ref oMissing);
            //QUITTING THE APPLICATION
            oWord.Quit(ref oMissing, ref oMissing, ref oMissing);